Influence of AlN/GaN strained multi-layers on the threading dislocations in GaN films grown by alternate supply of metalorganics and NH 3

Abstract

A series of AlN/GaN strained multi-layers having various thicknesses were grown either at low or high temperatures by an alternate supply of trimethylaluminum (TMA) and ammonia (NH 3) or trimethylgallium (TMG) and NH 3. Transmission electron microscopic (TEM) observations show that uniform AlN/GaN superlattices and multi-layers were achieved at high and low temperatures. These AlN/GaN multi-layers were observed to block the threading dislocations effectively for certain thicknesses and growth temperature. AlN/GaN (5 nm/5 nm) strained multi-layers deposited at 1050 °C right above the low temperature AlN buffer layers appear to reduce the density of threading dislocations in the high temperature (HT) GaN film grown subsequently. In particular, an insertion of low temperature (LT) pseudomorphic AlN/GaN strained multi-layers inside the HT-GaN film stops the propagation of threading dislocations very efficiently.